Introduction to Pvid and vid and switch ports

Pvid English is interpreted as the Port-base VLAN ID, which is a port based VLAN ID.

The vid is the meaning of the VLAN tag on the message.

The ports on the switch are divided into three kinds of access layer port direct-attached devices, called access; one is the port between the switch and the switch is called trunk, and there is a pattern of access and trunk mixed, called hybrid.

ACCESS:

The access port is responsible for receiving the terminal equipment, and he receives a frame when if the frame is not marked, he marks him with his own pvid, and when he emits a frame, if Vid=pvid removes the mark (the mark) to ensure that the frame transmitted to the terminal is not altered (the intermediary device adds a tag), Pvid is the attribute of each port when the VLAN is divided, by default, the initial pvid of each port in the Cisco switch is 1, indicating that he is a member of VLAN 1 if you divide the other VLANs for him then Pvid will change accordingly.

Pvid is not a tag that is added to the frame header, but rather a port property that identifies the unmarked frames that the port receives.

The access port is characterized by allowing only traffic that conforms to pvid.

TRUNK:

Trunk Relay links allow various VLANs to pass. When you receive a tag without tags, you mark it with your own pvid, and when you send a frame if Vid=pvid removes pvid, unlike access, Trunk has one of its own intrinsic VLANs ( The Native VLAN, also known as Pvid, is used to send data or manage traffic between switches such as CDP,BPDU, and frames generated from the switch themselves are not marked when emitted, because vid=pvid so the tag is removed, When the end receives the unmarked frame, it will tag him with the information of its own VLAN, then check the exchange table to remove the mark if the destination address is found. If you find that the destination MAC address is not yourself, continue forwarding to the other trunk while removing the tag (since a switch has only one intrinsic VLAN all pvid=vid minus the tag)

Hybrid:

Hybrid is the blending mode of access and trunk, which allows Vid=pvid. Hybrid, like trunk, can transmit packets of multiple VLANs on this port, typically between switches and switches, or between switches and servers. If a packet is received without a VLAN, then the pvid is forwarded, and if the packet is received with a VLAN, determine if the port allows the VLAN to enter, or if it can forward, discard

802.1Q VLAN is in the two-layer frame into the VLAN identification, commonly known as tag, and the computer can not parse the two-tier frame, so a switch port in a VLAN when the tag and Untag properties of two properties, tag port used to connect the device, The UNTAG port is used to connect to the computer. Tag port out of the frame is generally played tag,tag in the vid some from the pvid, some from the other tag port itself contains the tag frame.

When the device interconnects, the vid in the tag determines which VLAN a two-layer frame belongs to, and the computer does not have the function of playing tag, so only add a property to the port that connects the computer to determine which VLAN the unmarked frames the computer is issued to, and this property is Pvid.

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